钛合金在不同溶液中的电化学腐蚀行为

Electrochemical Corrosion Behaviors of Titanium Alloy in Different Solutions

针对钛合金Ti6Al4V在不同溶液(NaCl、NaBr、KBr)和不同溶液质量分数(6.5%、12.5%、18.5%)下的电化学腐蚀行为进行研究,得到了钛合金腐蚀极化曲线和腐蚀动力学参数;根据扫描电镜腐蚀图像研究了钛合金的电化学腐蚀机理;采用像素点覆盖分形维数法对腐蚀坑的分形特征进行了计算,得到了腐蚀表面形貌与分形的关系.研究结果表明:相比在NaBr溶液和KBr溶液中,钛合金在NaCl溶液中的活化范围更宽,氧化溶解时间更长,差异效应明显;相同质量分数下钛合金在NaBr溶液中的腐蚀性更强;随着质量分数增大,钛合金在3种溶液中的分形维数逐步变化——在NaBr溶液中的分形维数最大,表面形貌更为复杂,在NaCl溶液中的分形维数最小,表面形貌比较平整.

In this paper, first, the electrochemical corrosion behaviors of titanium alloy Ti6A14V were investigated in such different solutions as NaCl, NaBr and KBr at various mass fractions （6. 5% , 12.5% and 18.5% ） , and the corresponding corrosion polarization curves and dynamic parameters were obtained. Then, the electrochemical corrosion mechanism of titanium alloy was explored by means of SEM. Finally, the fractal feature of corrosion pits was obtained by means of the pixel-covering fractal dimension method, and the relationship between the corrosion surface topography and the fractal was revealed. The results show that （ 1 ） different from the titanium alloy in NaBr and KBr solutions, the titanium alloy in NaCl solution possesses wider activation range and longer oxidation dissolution time; （2） the corrosivity of titanium alloy in NaBr solution is stronger than that in NaCl and KBr solutions at the same mass fraction ; and （3） the fractal dimension of titanium alloy in the three kinds of solutions gra-dually changes with the increase of mass fraction; for instance, the fractal dimension in NaBr solution is the most, which results in the most complex topography, while that in NaCl solution is the least, which results in a relatively flat topography.